Sea levels around the globe are rising because of climate change. Temperatures in the atmosphere are going up because of greenhouse gas emissions, causing an increase in the melting of land-ice, and more importantly, raising the temperatures of the oceans’ surface and deeper waters. As water warms it expands (known as the 'thermal expansion' component of sea level rise, in contrast to the land ice component).
Other processes play a role as well. A local lowering of air-pressure of 10 mbar causes local sea level to rise 10 cm. Changes in ocean-currents, and even changes in the distribution of floating ice-masses like those that are diminishing in the Arctic, can all contribute to variations in sea level rise around the planet.
All these elements are modelled and expressed in the Global Climate Models (GCMs) which are publicly available from the Fifth Assessment Report (AR5) of the Intergovernmental Panel for Climate Change (IPCC). The CMIP5-data (Coupled Model Intercomparison Project Phase 5) of 28 GCM have been used to generate outputs in this App.
There is another critical and often overlooked factor that determines how sea level rise is experienced locally: land also moves up or down. This is usually a slow process but its magnitude is comparable to sea level rise. Thus when land rises, it lowers the rate of sea level rise experienced at that specific coastline, but when land sinks it exacerbates the local effects of sea level rise.
The app shows a global map of the combined processes of local (absolute) sea level rise and local vertical land movement. The sea level rise values are taken as the median value of an ensemble of 28 GCM’s, under the assumption of the largest greenhouse gas emissions as described by the RCP8.5 scenario in AR5. It also assumes a high climate sensitivity.
The vertical land movement values were generated from direct observations of continuous GPS (Global Positioning Systems; the SONEL program), and from trend analysis of tidal observations (the PSMSL program).
When a location is clicked on the map, the App shows a ruler with five future years (2020, 2040, 2060, 2080 and 2100), the sea level rise at these years compared to the baseline year of 1995 (in cm), the local Vertical Land Movement (in mm/year), and the variation over the months (in cm).